In order to insert prosthetic devices, such as partial or total knee replacements, it is, of course, necessary for the surgeon to remove sufficient bone to make room for the device and to prepare the cut ends of the bone to receive and anchor the prosthetic device. Heretofore, while reasonably accurate cutting was required to obtain a good fit, it could generally be done by a surgeon holding a saw in his hand as any small errors could be corrected by judicious application of the cement used to secure the prosthesis to the bone. Modern techniques, however, which include the use of porous coated prostheses to promote bone ingrowth, do not permit the use of adhesives and hence minor alignment deficiencies cannot be corrected in this way. It becomes critical that the surgeon's bone cuts are accurate to within a few thousandths of an inch and such accuracy is impossible to attain with a hand held saw. Numerous attempts have been made to use a variety of jigs which stabilize the cutting blade in a predetermined direction while the saw is held in the surgeon's hand. Each cut requires a different jig as does each design of prosthesis, of which there are many. Furthermore, the jigs themselves tend to flex the blade during cutting thus reducing the chances for an accurate square cut. In our earlier filed application referred to above, there is described a slide bed device for mounting an orthopaedic saw or other bone cutting device so as to provide three accurately controlled degrees of freedom of movement of the cutting device. The cutting device is slidably mounted on a vertical stand for movement in a vertical plane, and the vertical stand is in turn mounted perpendicularly on two relatively movable horizontal slides at right angles to each other. The horizontal slides are mounted on a three point frame which may be adjustably mounted directly onto the bone to be cut in a plane parallel the longitudinal axis of the bone. While this device solves most of the problems of the prior art, it has been found to require extensive surgical exposure and, furthermore, to require a change in positions of the leg to allow completion of the bone cuts--requiring a fresh set up and re-alignment to be undertaken.